WIP: Class authoring format.

package.json

@@ -33,7 +33,7 @@
     "@web/test-runner-puppeteer": "^0.14.2",
     "http-server": "^14.1.1",
     "jasmine-core": "^4.5.0",
-    "typescript": "^4.9.4"
+    "typescript": "^5.3.3"
   },
   "files": [
     "/*.js",

src/component-class.ts

@@ -0,0 +1,38 @@
+import { ComponentRef } from './component-ref.js';
+import { ElementRef } from './element-ref.js';
+import { HydroActiveComponent } from './hydroactive-component.js';
+import { Signal } from './signals.js';
+
+/** TODO */
+export abstract class Component<State extends {} = {}>
+    extends HydroActiveComponent {
+  protected readonly ref = ElementRef.from(this);
+  protected readonly comp = ComponentRef._from(this.ref);
+
+  #state: State | undefined;
+  protected get state(): State {
+    if (!this.#doneHydrating) {
+      throw new Error('`state` is not accessible during hydration.');
+    }
+
+    return this.#state!;
+  }
+
+  protected get props(): Record<string, Signal<unknown>> {
+    return new Proxy(this, {
+      get(target: Component<State>, prop: string | symbol): Signal<unknown> {
+        const propName = typeof prop === 'symbol' ? prop.description : prop;
+        const internalProp = `_${propName}`;
+        return (target as any)[internalProp];
+      }
+    }) as unknown as Record<string, Signal<unknown>>;
+  }
+
+  #doneHydrating = false;
+  protected override hydrate(): void {
+    this.#state = this.onHydrate() ?? ({} as State);
+    this.#doneHydrating = true;
+  }
+
+  protected abstract onHydrate(): State | undefined;
+}

src/demo/auto-counter.ts

@@ -1,42 +1,57 @@
-import { component } from 'hydroactive';
-import { cached, signal } from 'hydroactive/signals.js';
-
-const Serializer = Symbol('HydroActiveSerializer');
-class User {
-  public constructor(private name: string) {}
-
-  static [toSerializer](): Serializer<User> {
-    return {
-      serialize(user: User): string {
-        return JSON.stringify({ name: user.name });
-      },
-
-      deserialize(serial: string): User {
-        const { name } = JSON.parse(serial);
-        return new User(name);
-      },
-    };
-  };
+import { Component } from 'hydroactive';
+import { WriteableSignal, property, signal } from 'hydroactive/signals.js';
+
+// Need to define an interface.
+interface State {
+  readonly count: WriteableSignal<number>;
 }
 
-/** Automatically increments the count over time. */
-export const AutoCounter = component('auto-counter', (comp) => {
-  const label = comp.host.query('span');
-  const count = signal(Number(label.text));
-  const doubleCount = cached(() => count() * 2);
-
-  comp.connected(() => {
-    const id = setInterval(() => {
-      count.set(count() + 1);
-    }, 1_000);
-
-    return () => {
-      clearInterval(id);
-    };
-  });
-
-  comp.effect(() => {
-    label.native.textContent = count().toString();
-    console.log(`Double count: ${doubleCount()}`);
-  });
-});
+class AutoCounter extends Component<State> {
+  // Need to define the property twice to get an internal and external type.
+  @property()
+  public accessor incrementBy = 2;
+
+  protected override onHydrate() {
+    const label = this.ref.query('span')!;
+    const count = signal(Number(label.text));
+
+    this.comp.connected(() => {
+      const id = setInterval(() => {
+        // Too easy to accidentally use `this.incrementBy` and get a
+        // non-reactive value.
+
+        // No way to type `this.props` based on `@property` accessors?
+        count.set(count() + (this.props['incrementBy']!() as number));
+      }, 1_000);
+      return () => clearInterval(id);
+    });
+
+    this.comp.effect(() => {
+      label.native.textContent = count().toString();
+    });
+
+    // Can't use `this.state` here or in any called function.
+    // `this.state.count()` -> Error.
+    // At least can do a decent error.
+
+    // Not clear that this is the initial value of `this.state`.
+    return { count };
+  }
+
+  // Have to prefix `this.state` everywhere except the `hydrate` function.
+  public increment(): void {
+    this.state.count.set(this.state.count() + 1);
+  }
+
+  public decrement(): void {
+    this.state.count.set(this.state.count() - 1);
+  }
+}
+
+customElements.define('auto-counter', AutoCounter);
+
+declare global {
+  interface HTMLElementTagNameMap {
+    'auto-counter': AutoCounter;
+  }
+}

src/index.ts

@@ -1,3 +1,4 @@
 export { HydrateLifecycle, component } from './component.js';
+export { Component } from './component-class.js';
 export { ComponentRef, OnDisconnect, OnConnect } from './component-ref.js';
 export { ElementRef } from './element-ref.js';

src/signals/index.ts

@@ -1,5 +1,6 @@
 export { cached } from './cached.js';
 export { effect } from './effect.js';
+export { property } from './property.js';
 export { Equals, signal } from './signal.js';
 export { MacrotaskScheduler } from './schedulers/macrotask-scheduler.js';
 export { Action, CancelAction, Scheduler } from './schedulers/scheduler.js';

src/signals/property.ts

@@ -0,0 +1,28 @@
+import { Component } from 'hydroactive';
+import { Signal, WriteableSignal } from './types.js';
+import { signal } from './signal.js';
+
+type SignalPropertyDecorator<Comp extends Component, Value> = (
+  target: ClassAccessorDecoratorTarget<Comp, Value>,
+  context: ClassAccessorDecoratorContext<Comp, Value>,
+) => ClassAccessorDecoratorResult<Comp, Value> | void;
+
+export function property<Comp extends Component>(): SignalPropertyDecorator<Comp, any> {
+  return (_target, ctx) => {
+    const propName = typeof ctx.name === 'symbol' ? ctx.name.description : ctx.name;
+    const internalProp = `_${propName}`;
+    return {
+      init(value): void {
+        (this as any)[internalProp] = signal(value);
+      },
+
+      get(): unknown {
+        return ((this as any)[internalProp] as Signal<unknown>)();
+      },
+
+      set(value: unknown): void {
+        ((this as any)[internalProp] as WriteableSignal<unknown>).set(value);
+      },
+    };
+  };
+}

tsconfig.base.json

@@ -16,8 +16,8 @@
     "target": "es2022",                                  /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
     // "lib": [],                                        /* Specify a set of bundled library declaration files that describe the target runtime environment. */
     // "jsx": "preserve",                                /* Specify what JSX code is generated. */
-    "experimentalDecorators": true,                      /* Enable experimental support for TC39 stage 2 draft decorators. */
-    "emitDecoratorMetadata": true,                       /* Emit design-type metadata for decorated declarations in source files. */
+    // "experimentalDecorators": true,                   /* Enable experimental support for TC39 stage 2 draft decorators. */
+    // "emitDecoratorMetadata": true,                    /* Emit design-type metadata for decorated declarations in source files. */
     // "jsxFactory": "",                                 /* Specify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h'. */
     // "jsxFragmentFactory": "",                         /* Specify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'. */
     // "jsxImportSource": "",                            /* Specify module specifier used to import the JSX factory functions when using 'jsx: react-jsx*'. */
@@ -27,7 +27,7 @@
     // "moduleDetection": "auto",                        /* Control what method is used to detect module-format JS files. */
 
     /* Modules */
-    "module": "es2020",                                  /* Specify what module code is generated. */
+    "module": "Node16",                                  /* Specify what module code is generated. */
     "rootDir": "src/",                                   /* Specify the root folder within your source files. */
     "moduleResolution": "Node16",                        /* Specify how TypeScript looks up a file from a given module specifier. */
     "baseUrl": "./",                                     /* Specify the base directory to resolve non-relative module names. */